Modern agriculture aims to reduce continuous applications of synthetic chemical pesticides for pest control because of issues such as pollution, loss of trade and disruption of biological control agents, potentially leading to pest outbreaks. Botanical insecticides are a good alternative to synthetic pesticides, as they have lower environmental hazard, are biodegradable and can be used shortly before harvesting. We tested the effect of essential oils (EOs) and aqueous extracts (AEs) of Chenopodiaceae plants (Dysphania ambrosioides (=Chenopodium ambrosioides), Chenopodium album, C. berlandieri subsp. nuttalliae, C. graveolens and Beta vulgaris), incorporated into the diet under lab conditions, on a widely distributed insect pest in America, the cabbage pest, Copitarsia decolora Guenée 1852 (Lepidoptera: Noctuidae). The EO of C. graveolens at 0.5% reduced the larvae and pupae weight by 30 and 15%, respectively; increased the larval period length by 17% and reduced fecundity and fertility by 80 and 85%, respectively related to the control. EOs of C. berlandieri and B. vulgaris at 0.5% increased larval and pupal period length by 22% and 38% and both reduced fecundity and fertility by 99% related to the control. None of the plant extracts tested caused immediate C. decolora mortality, but EOs reduced mean survival time and reproductive capacity of the insect. This is the first report of C. berlandieri EO effect against an insect pest. The EOs of C. graveolens, B. vulgaris and C. berlandieri have great potential as alternatives to synthetic chemicals for insect control and deserve further exploration.